Tyrphostin AG1478对重组人蛋白激酶CK2全酶的抑制作用及其动力学分析

目的:观察Tyrphostin AG1478[4-(3-氯苯胺基)-6,7-二甲氧喹唑啉]对重组人蛋白激酶CK2全酶的直接作用及其酶动力学机制.方法:在体外等摩尔数混合重组蛋白激酶CK2α和β亚基构成CK2全酶,在不同条件下测定CK2的活性.CK2活性通过测定转移到CK2底物上的[γ-~(32)P]ATP或[γ-~(32)P]GTP的~(32)P放射活度来检测.结果:重组人CK2是一种Ca~(2 )、[KG*2]cAMP和cGMP等第二信使非依赖性蛋白激酶,与天然CK2的性质一致.AG1478对重组人CK2全酶具有很强的抑制作用,IC_(50)为25.9μmol/L,抑制作用接近于已知的CK2抑制剂N-(2-氨乙基)-5-氯萘-1-硫胺(A3),稍小于5,6-二氯-1-β-呋喃糖苯并咪唑(DRB).AG1478对重组人CK2的动力学研究表明:它与GTP和酪蛋白均呈竞争性抑制作用,是一种双底物抑制剂.结论:AG1478不仅是高效特异的表皮生长因子受体酪氨酸蛋白激酶的抑制剂,而且也是一种新型有效的蛋白激酶CK2抑制剂.重组人蛋白激酶CK2可作为一种较为简便的筛选和开发有效CK2抑制剂的分子靶点.

Inhibitory effect and its kinetic analysis of tyrphostin AG1478 on recombinant human protein kinase CK2 holoenzyme

AIM: To study the direct effect of tyrphostin AG1478 [4-(3-chloroanilino)-6,7-dimethoxyquinazoline] on recombinant human protein kinase CK2 holoenzyme and its kinetics. METHODS: Recombinant human protein kinase CK2 alpha and beta subunits were mixed at equal molar ratio and CK2 holoenzyme were reconstituted. The CK2 activity was assayed by detecting incorporation of [gamma-32P]ATP or [gamma-32P]GTP into substrates in various conditions. RESULTS: These results demonstrated that the recombinant human CK2 was a second messengers (Ca2+, cAMP, and cGMP)-independent protein kinase, the characterization and function of the reconstituted holoenzyme were consistent with those of native CK2. AG1478 strongly inhibited the holoenzyme activity of recombinant human protein kinase CK2 with IC50 of 25.9 micromol/L, the inhibition is very close to that of N-(2-aminoethyl)-5-chloronaphthalene-1-sulfonamide (A3), but less potent than that of 5,6-dichloro-1- beta-D-ribofuranosylbenzimidazole (DRB), known as CK2 special inhibitors with IC50 of 25.5 micromol/L and 10.4 micromol/L respectively. Kinetic studies of AG1478 on recombinant human CK2 showed that inhibitions were competitive with both GTP and casein, thus AG1478 was as bisubstrate inhibitor. CONCLUSION: The present study indicates that AG1478 is not only an effective inhibitor of protein tyrosine kinases of epidermal growth factor receptor (EGFR), but also a novel potent inhibitor of protein kinase CK2. The recombinant human protein kinase CK2 might be used as a molecular target for simpler screening and development of more effective inhibitors of CK2.